[gdal-dev] bigtiff support maybe not working

[Even Rouault]

Margherita,

> # GDAL cache in megabytes
> CACHE="--config GDAL_CACHEMAX 8000 -wm 8000"
>

BigTIFF support likely works as expected. In that instance, the error comes from
the huge value used for the -wm option of gdalwarp. Try to keep it below 2000.
If I remember well, there must be a sanity check in the warping algorithm to
prevent allocation of buffers above 2 GB, to avoid errors in 32bit environmenet.
And in 64bit builds, there's little gain to expect from such huge values anyway.
The GDAL_CACHEMAX value is also probably much bigger than really needed. In any
case, you must make sure that the available RAM is at least the sum of the 2
values, otherwise you'll get into disk swapping, which will anihilate the
benefit of those optimizations.

If you are playing with cache values, you must make sure to read and understand
http://trac.osgeo.org/gdal/wiki/UserDocs/GdalWarp#WillincreasingRAMincreasethespeedofgdalwarp
. To sum it up : "bigger is not necessarily better"

But you could likely benefit from adding -co TILED=YES to produce a tiled
GeoTIFF.

And specifying -co BIGTIFF=YES is rarely needed. Recent GDAL builds will figure
automatically if BigTIFF is necessary for uncompressed files. If you ask for
compressed GeoTIFF, the heuristics might fail and the explicit BIGTIFF=YES
option might be necessary.

Best regards,

Even